It is known to use magnetic separation in order to extract ferromagnetic components from a starting material. To this end one or more magnets are provided, which generate a magnetic field that interacts with the ferromagnetic particles contained in the starting material and attract them, so that separation is possible in principle. An example of the use of such magnetic separation is the recovery of ferromagnetic Fe3O4 particles from a suspension, as is encountered for example in the scope of extracting Cu2S particles from ground ore. In this case, the ore as a raw material is initially ground finely; besides other substantial components (sand etc.) it also contains Cu2S in a small amount. In order to separate this nonmagnetic material, the ground ore powder is processed with a carrier liquid to form a suspension, Fe3O4 (magnetite) being added to this suspension together with one or more chemical agents which ensure hydrophobizing by organic molecule chains that accumulate both on the Cu2S particles and on the Fe3O4 particles. By means of these organic molecule chains, agglomeration then takes place in which Fe3O4 particles accumulate on one or more Cu2S particles, and thus substantially encapsulate them. By means of magnetic separation, it is then possible to extract these larger multicomponent agglomerates.
All magnetizable substances suitable for this purpose will be referred to below generically as “Fe3O4”, this also being intended to include all other ferrites, oxides and metal compounds and alloys which are sufficiently chemically inert. Likewise, the term “Cu2S” stands generically for all valuable ores extracted in mining, and therefore also covers pure noble metals and compounds thereof, as well as all sulfidic, oxidic and other metal compounds.
This separation process is subsequently followed by another possible magnetic separation process, since it is subsequently necessary to separate these agglomerates that have been formed, which were merely formed to permit magnetic separation of the nonmagnetic Cu2S, since on the one hand the Fe3O4 needs to be recovered and on the other hand the purpose of the processing is to extract the Cu2S. To this end, by means of various techniques, the organic compounds inside the agglomerates, by means of which the Cu2S particles and the Fe3O4 particles are connected to one another, are broken up so that the suspension contains the separate dissolved particles, from which in turn the Fe3O4 particles can be subsequently separated by means of a magnetic separating device and subsequently reused, while the nonmagnetic Cu2S particles remain in the suspension and can subsequently be separated from it.
To date, it has been conventional to use a tubular reactor for the separation, through which the material to be magnetically treated flows. One or more magnets are arranged locally fixed on the outer wall of the reactor, these attract the ferromagnetic material contained, and the material migrates to the reactor wall and is held by the neighboring magnet. Although this allows effective separation, it only permits a batch separation process since after a sufficient amount of agglomerate has accumulated, the suspension has to be taken from the reactor and only then can the ferromagnetic agglomerates, which have thus far been fixed on the wall by means of the magnets, be extracted. A new separation cycle can then be started.